Bryce, I wrote an essay on that and it is included in The Earth Reeled and Trees Trembled, which is available at the Old State House Museum.

The following article also is excellent:

Thunder across the Arkansas prairie: Shelby's opening salvo in the 1864 invasion of Missouri
Porter, Scott A.
Arkansas Historical Quarterly 66(1):43-56 Spr 2007.

Hope this helps!

Mark